Transmission line for use in magnetic resonance system

Abstract

An electrically conductive transmission cable for supplying a DC signal safely to an electrical device in the presence of radio-frequency (RF) fields in a magnetic resonance (MR) is disclosed herein. The transmission cable comprises a transmission line (STL) comprising at least a first segment (S1) and a second segment (S2), wherein the first and second segments are electrically connected to each other by a reactive coupling unit (103), and a rectifier unit (101) connected to the transmission line and configured to extract the DC signal (203) from the modulated DC signal (201). The extracted DC signal may be supplied to an electrical device or used for cardiac pacing. The transmission cable finds application in auxiliary devices used in an MR environment, for example an interventional catheter with or without an active tracking circuit (301).

Description

FIELD OF THE INVENTION[0001]The invention relates to the field of magnetic resonance (MR), particularly to transmission of electrical currents in the presence of radio-frequency (RF) fields.BACKGROUND OF THE INVENTION[0002]U.S. Pat. No. 7,750,637 discusses a transmission line that is especially provided for connecting an electrical device, like for example an accessory device of an MR imaging system, to a connection unit, like for example a power supply or a control unit. The transmission line is also suitable for connecting implants especially with long conductors or electrodes, like for example heart pacemakers or artificial nerves, for supplying power to preamplifiers, for MR compatible IVUS (intravascular ultrasound) devices, for tracking of catheters or guide wires during MR image generation, and other applications which require a transmission line which is safe when guided through an RF field (for example generated by an MR imaging system). The transmission line comprises at l...

AI Technical Summary

Benefits of technology

The patent text describes a transmission cable that can safely transmit DC signals in the presence of RF fields. This is important for cardiac interventions where the catheter needs to provide three basic functionalities: mapping of the intracardiac electrocardiogram signals, transmitting DC pacing signals for cardiac pacing, and supplying DC power for RF ablation of tissue. The cable uses a transformer-based transmission line to suppress tip heating and a highly resistive wire for low frequency signals. The cable is designed to receive a modulated DC signal and extract it for use in pacing the heart. This invention allows for the safe use of standard electrophysiology catheters in an MR environment.

Problems solved by technology

Using MR as an imaging modality for guiding catheter interventions imposes restrictions on the equipment used, since conducting structures, like a long metallic wire or cable, inside an MR-system are susceptible to RF-heating, especially at the tip of the conducting structures.

However, providing safe DC-power transmission in the presence of RF fields, as required for example for cardiac pacing or for RF ablation, is more difficult.

Thus standard electrophysiology catheters, which employ conducting wires for signal transmission, are not usable in an MR environment.

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